Preheat oven to 350°F. Grease three 6-inch cake pans with baking spray.
In a large mixing bowl, beat cake mix, eggs, milk, and melted butter for 1-2 minutes until just combined. Do not overmix.
Divide batter evenly among pans and bake for 18-25 minutes or until a toothpick comes out clean and the tops spring back when touched.
Cool cakes in pans for 10 minutes, then transfer to a cooling rack to cool completely.
While cakes cool, beat cream cheese frosting, mascarpone, and vanilla until light and creamy (1-2 minutes). Refrigerate until ready to use.
To assemble, level the first cake layer if needed. Mix simple syrup and espresso powder in a small bowl. Microwave for 30 seconds and stir until dissolved.
Brush espresso syrup generously over the cake layer. Using a piping bag fitted with a 2A tip, pipe a frosting border and fill the center. Smooth evenly.
Repeat with remaining layers, soaking each with syrup and adding frosting before stacking.
Frost the outside of the cake, smoothing it with a spatula. Optionally, pipe decorative dollops on top.
Dust with cocoa powder. Refrigerate for 30-60 minutes before slicing and serving.
Notes
🥡 STORAGE
Store the cake in the refrigerator, covered with plastic wrap or in an airtight container, for 3-4 days
Use a cake container to protect the frosting and keep it fresh
♨️ REHEATING
This cake is best served cold or at room temperature
No reheating is needed
❄️ FREEZING
Wrap unfrosted cake layers tightly in plastic wrap and freeze for up to 3 months
Thaw in the refrigerator overnight before assembling
Frosted cake can also be frozen, but may lose some texture
💡 TIPS FOR BEST RESULTS
Use room temperature eggs and milk for smoother batter
Chill the frosting before assembly to help it hold its shape
Level cake layers for even stacking
Adjust espresso powder to taste for more or less coffee flavor
Refrigerate the finished cake for at least 30 minutes before slicing
🍳 ALTERNATE COOKING METHODS
Oven only - no other alternate cooking methods are recommended for this cake
♻️ LEFTOVERS
Store individual slices in airtight containers in the fridge
Enjoy leftovers cold or let them sit at room temperature for 15-20 minutes before serving